Discuss Three phases main supply in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net
It doesn't ALWAYS have to be like that.
They could all be brown, but marked up as L1, L2, L3
There is a requirement to ensure correct phase rotation throughout an Installation in Chapter 6.
I think it’s a bit pointless, as when you connect 3 phase machinery, if it runs backwards, you just swap one of the phases over.
Agree but you can do that at the machine can't you? thus not altering the phase sequence at the incoming supply to the machine switchgear.There is a requirement to ensure correct phase rotation throughout an Installation in Chapter 6.
I think it’s a bit pointless, as when you connect 3 phase machinery, if it runs backwards, you just swap one of the phases over.
Yes you can do that at the machine.Agree but you can do that at the machine can't you? thus not altering the phase sequence at the incoming supply to the machine switchgear.
I was trying to make the point that the phase sequence wouldn't change at the point of connection to the equipment from the supply, if you wanted to keep the sequence the same throughout, that's all.Yes you can do that at the machine.
But what’s the point in ensuring phase rotation is consistent throughout an installation?
You have an installation where phase rotation has been checked throughout.
You install a new machine, it runs backwards.
You swap the phases round in the machine, it runs forwards.
You have an installation where phase rotation has not been checked throughout.
You install a new machine, it runs backwards.
You swap the phase round in the machine, it runs forwards.
What’s the difference?
i'd never sleeve black and grey with brown on a 3 phase installation. we never sleeved the yellow and blue. only brown sleeve when used in single phase circuit/s.It doesn't ALWAYS have to be like that.
They could all be brown, but marked up as L1, L2, L3
If you're referring to how a 3 core cable connects to one of the old colours, then yes... its
L1 - Red - Brown
L2 - Yellow - Black
L3 - Blue - Grey
Black and grey sleeved with brown to denote line conductors
Yes you can do that at the machine.
But what’s the point in ensuring phase rotation is consistent throughout an installation?
When I was in the RAF we had a hangar with 6 separate bays where we moved 3 phase machines with 125A plugs around depending on aircraft requirements. Bay 2 (I can even picture it right now) was wired the wrong way round meaning that every time a machine went in or out of there one of us had to swap the phases round. Our contractors were like you and couldn’t see the problem. Hours of work over years due to incompetence on the part of the original inspector that signed it off.Yes you can do that at the machine.
But what’s the point in ensuring phase rotation is consistent throughout an installation?
You have an installation where phase rotation has been checked throughout.
You install a new machine, it runs backwards.
You swap the phases round in the machine, it runs forwards.
You have an installation where phase rotation has not been checked throughout.
You install a new machine, it runs backwards.
You swap the phase round in the machine, it runs forwards.
What’s the difference?
That’s probably a scenario where checking the phase rotation would be a good idea.When I was in the RAF we had a hangar with 6 separate bays where we moved 3 phase machines with 125A plugs around depending on aircraft requirements. Bay 2 (I can even picture it right now) was wired the wrong way round meaning that every time a machine went in or out of there one of us had to swap the phases round. Our contractors were like you and couldn’t see the problem. Hours of work over years due to incompetence on the part of the original inspector that signed it off.
Black and grey sleeved with brown to denote line conductors
If phase conductors are being used as single phase line conductors, then they should all be sleeved brown.Only if they are all on the same phase, if they are on different phases they should not be sleeved.
If phase conductors are being used as single phase line conductors, then they should all be sleeved brown.
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